static int binder_translate_fd()

in binder.c [2173:2234]

• 52 lines of code
• 7 McCabe index (conditional complexity)

static int binder_translate_fd(u32 fd, binder_size_t fd_offset,
			       struct binder_transaction *t,
			       struct binder_thread *thread,
			       struct binder_transaction *in_reply_to)
{
	struct binder_proc *proc = thread->proc;
	struct binder_proc *target_proc = t->to_proc;
	struct binder_txn_fd_fixup *fixup;
	struct file *file;
	int ret = 0;
	bool target_allows_fd;

	if (in_reply_to)
		target_allows_fd = !!(in_reply_to->flags & TF_ACCEPT_FDS);
	else
		target_allows_fd = t->buffer->target_node->accept_fds;
	if (!target_allows_fd) {
		binder_user_error("%d:%d got %s with fd, %d, but target does not allow fds\n",
				  proc->pid, thread->pid,
				  in_reply_to ? "reply" : "transaction",
				  fd);
		ret = -EPERM;
		goto err_fd_not_accepted;
	}

	file = fget(fd);
	if (!file) {
		binder_user_error("%d:%d got transaction with invalid fd, %d\n",
				  proc->pid, thread->pid, fd);
		ret = -EBADF;
		goto err_fget;
	}
	ret = security_binder_transfer_file(proc->cred, target_proc->cred, file);
	if (ret < 0) {
		ret = -EPERM;
		goto err_security;
	}

	/*
	 * Add fixup record for this transaction. The allocation
	 * of the fd in the target needs to be done from a
	 * target thread.
	 */
	fixup = kzalloc(sizeof(*fixup), GFP_KERNEL);
	if (!fixup) {
		ret = -ENOMEM;
		goto err_alloc;
	}
	fixup->file = file;
	fixup->offset = fd_offset;
	trace_binder_transaction_fd_send(t, fd, fixup->offset);
	list_add_tail(&fixup->fixup_entry, &t->fd_fixups);

	return ret;

err_alloc:
err_security:
	fput(file);
err_fget:
err_fd_not_accepted:
	return ret;
}